Electronic annunciator improvements



Nov. 16, 1955 G. E. FOSTER ELECTRONIC ANNUNCIATOR IMPROVEMENTS FiledAug. 15. 1960 LIGHT OFF SOUND -OFF F LASH L\GHT FLASH [SOUND-BUZZ 4Sheets-Sheet 1 UGHT- FLASH SOUND HORN ALARM" L\G HT 5TB ADV SOUND-OFF-FJL g; 2 ANNUNCJATOR 200 2,

SUPERVISORY /40 FLASHER cmcurr 400 l 300 0 401ZL 400A 1 SOUNDER L 40055,1 4 4oa i -49o fJI 3 429 L@ 425 OR 420 405 408 428 Kj mam 4/4 AND I427 l l 424 OR 4/5 435 31 fgf 4o7 4:2 402 359 39 5 AND 426 500 INVENTOR.GEORGE. E. FOSTER 4/1 490 MEM BY 425 F gm pmwl Nov. 16, 1965 G. E.FOSTER 3,218,621

ELECTRONIC ANNUNCIATOR IMPROVEMENTS Filed Aug. 15, 1960 4 Sheets-Sheet 2FROM OTHER SUPERVISORY CIRCUITS TO OTHER SUPERVISOR! Q22 CJRCLHTS FROM402 FLASHER SOUNDER 500 TO LOUD SPEAKER INVENTOR. GEORGE E. FOSTER Nov.16, 1965 e. E. FOSTER 3,218,621

ELECTRONIC ANNUNCIATOR IMPROVEMENTS Filed Aug. 15. 1960 4 Sheets-Sheet 3625A 1 6 601A o 690 0A SUPERVlSORY ClRCUlT 600 i i-I -O SOUNDER Ll Q- 7TO SOUNDER C 0&0 AND OTHER SUPERWSORY 70/ 7/0 cmcuws l c4o INVENTOR.GEORGE E. Fos-r ER 3,21 &1

Nov. 16, 1965 G. E. FOSTER ELECTRONIC ANNUNCIATOR IMPROVEMENTS 4Sheets-Sheet 4 Filed Aug. 15, 1960 INVENTOR. GEORGE E. FOSTER BY 31 PM WWW EUDZ DOW OP NQQ mm-IwdJ u EON-u mwIkO ZONE H mwDZDOm OP um l luUnited States Patent 3,218,621 ELECTRONIC ANNUNCIATOR MPROVEMENTS GeorgeE. Foster, 7917 S. Yale, Chicago, Ill. Filed Aug. 15, 1960, Ser. No.49,670 2 Claims. (Cl. 340-2132) This invention relates in general toannunciators and more particularly to improvements in an annunciatorsystem of the type disclosed in application No. 9,925 filed February 19,1960 by the applicant herein.

This application is therefore a continuation-in-part of theaforementioned application, wherein an annunciator arrangement wasdisclosed comprising a number of electronic gate or supervisory circuitsfor monitoring respective locations and arranged to control a commonsounder circuit. On receiving a signal indicating a trouble or faultcondition from a respective location each supervisory circuit signalledan elert condition to an attendant by flashing a lamp individual theretoand operating the common sounder circuit to provide an audible signalindicating an alert condition. It will be understood that the use of theterms fault or trouble are used herein merely to in dicate a departurefrom normal and that they are primarily illustrative of the mostfrequent type of use for annunciators in detecting apparatusmalfunctioning, but that the annunciator arrangements described hereinare capable of being used in numerous types of call systems.

The alert condition could be irreversible and therefore regardless ofthe nature of the fault condition the annunciator remained in the alertcondition, until the attendant acknowledged occurrence of the signal byoperating an acknowledgment key which placed the circuits in a certaincondition. When the trouble condition was cleared, a signal resultedthat enabled the supervisory circuit to again operate the sounder andflash the lamp which informed the attendant of this condition known asthe flash condition. He then again acknowledged by operating the key toreset the equipment in a normal condition. If, while the annunciator wasin the flash condition, the trouble or fault condition should reoccur,the attendant might not be informed of this, without performing anacknowledgment operation. In addition, the common sounder was operatedin the same manner responsive to either the alert or flash conditions,so that the attendant was not automatically informed of the difierencein the two conditions or states.

The circuits disclosed in that application, however, represented aconsiderable forward step in annunciator systems in that they utilizedsolid state elements in an unusually economical design. Previouslyannunciators had incorporated standard relay components which sufferfrom a number of disadvantages including the likelihood of theinoperability, when needed, due to such causes as contact corrosion orburning, but until the arrangement disclosed in the forementionedapplication was devised it was economically unfeasible to supplantrelays with solid state elements. This was most likely due to theconception that a solid state element must ordinarily be provided foreach movable contact set provided in a relay system, and as the solidstate elements are considerably more expensive than contact sets, thecost of such an installation would be considerable.

In the present invention several novel annunciator circuit arrangementsare provided utilizing solid state elements in circuits having similaradvantages to those disclosed in the aforementioned application. Thesecircuits are arranged to permit the annunciator to signal a reversion ofa fault to normal when in the alert condition and to signal a reversionto a fault when in the flash condition. Further, the common sounder andsupervisory circuits 3,218,621 Patented Nov. 16, 1965 ice incorporatenovel economical circuit designs which permit the sounder to be operatedin distinctively indicating modes when indicating an initial trouble oralert condition and when indicating the clearing of the trouble or aflash condition. This automatically informs the attendant whether theannunciator is in the alert or flash condition. Further improvementresides in adapting certain of the circuits described in theaforementioned application for operation with the sounder illustratedherein to provide the advantageous results described.

It is therefore an object of the present invention to provide anelectronic annunciator of improved versatility..

It is another object of this invention to provide a sound controlarrangement for an annunciator that is capable of providing a pluralityof difierent sounds each signalling a different annunciator condition.

It is still another object of this invention to provide a monitoring orsupervisory circuit for use in an annunciator to reversibly control theannunciator signalling sequence.

It is an additional object of this invention to provide a supervisorycircuit such as described that may be used to operate with differenttypes of sound control equipment.

It is still a further object of this invention to provide an electronicannunciator system having a signalling sequence including signals ofdifierent types of which one type has precedence over a signal ofanother type.

It is yet another object of this invention to provide a signalarrangement in an electronic annunciator that functions to provide soundsignals of different types responsive to diiferent conditions of theannunciator.

It is yet a further object of this invention to provide in anannunciator having a plurality of diiferent conditions, signals eachindividual to a different condition and to provide means for terminatingone of said signals and operating another irrespective of the conditionof said annunciator.

With the foregoing and other objects in view which will appear as thedescription proceeds, the invention consists of certain novel circuitsand features and a combination of parts hereinafter fully described,illustrated in the accompanying drawing, and particularly pointed out inthe appended claims it being understood that various changes in the formand minor details of the circuits and apparatus may be made withoutdeparting from the spirit or sacrificing any of the advantages of theinvention.

For the purpose of facilitating an understanding of this invention,there is illustrated in the accompanying drawing a preferred embodimentthereof, from an inspection of which, when considered in connection withthe following description, this invention, its mode of construction,assembly and operation, and many of its advantages should be readilyunderstood and appreciated.

Referring to the drawing in which the same reference characters areemployed wherever possible to indicate corresponding or similar partsthroughout the several figures of the drawing:

FIG. -1 is a diagrammatic illustration of the operative sequence. of theannunciator to be described in connection with FIGS. 2, 3, 4 and 5.

FIG. 2 is 'a block diagram of the annunciator whose operative sequenceis shown in FIG. 1.

FIG. 3 is a block diagram of one of the supervisory circuits shown inFIG. 2 and shown in detail in FIG. 4.

FIG. 4 illustrates the circuit details of one of the supervisorycircuits contained in the block diagram in FIG. 2.

FIG. 5 illustrates the circuit details of the sounder shown in the blockdiagram in FIG. 2.

FIGS. 6 and 7 are simplified supervisory circuit arrangements for use inan annunciator having a slightly different operative sequence from theannunciator shown in FIG. 1; and

FIG. 8 is a supervisory circuit for monitoring a plurality of differentlocations and utilizing an operative sequence such as disclosed in theaforementioned application but arranged for operation with a sounder ofthe type disclosed herein.

Referring now to FIGS. 1 and 2 it will be noted that the annunciatordesignated 200 in FIG. 2 may be in any one of the four condtiionsindicated in FIG. 1. That is, it may be in either normal, alert, alarmor flash condi tions. Each of these conditions represents a differentstate of one or more of the supervisory circuits 400, 400A and 400Bforming part of the annunciator 200. Each supervisory circuit 400, 490Aand 4008 monitors at least one location for a trouble or fault signal.The monitored locations are individual to the various supervisorycircuits and each represents a remote point or location at which variousapparatus may be located. When the monitored apparatus is functioningnormally, this apparatus is arranged to provide an electrical signal ofone type to its respective supervisory circuit. Such type of signal mayinclude a signal of no aflirmative polarity, if the monitored apparatusis not functioning properly it is arranged to transmit a signal ofdifferent character to its respective supervisory circuit. Such atransmitted signal may be one of a defined polarity or it may be one ofa polarity opposite to that of the above noted one type.

Thus, if all the monitored location points are functioning normally, theannunciator 200 is in normal condition; namely, neither light nor soundis provided. The light or sound, just referred to, means a light orsound other than normal status light or sound. If one or more of themonitored locations develops a fault or trouble, at corresponding signalis transmitted to the respective supervisory circuit 400, 400A or 400B.The supervisory circuit then controls the annunciator 200 to indicatethe alert condition by a respectively associated flashing lamp 475 andby operating the common sounder 500. This sounder thus provides a hornor warble sound. Hence, an attendant at the annunciator station isinformed of the alert condition. He is informed too of the origin orlocation of the fault or trouble.

In the diagram of FIG. 1, the alert condition is reversible. Thisreversibility is indicated by the double arrow heads on the line 100between the normal and alert conditions. Thus, if the trouble conditionshould be temporary and should be cleared, the annunciator 200 revertsback to the normal condition. The flashing light and horn or warblesound indicating the alert condition are thus automatically turned off.

The attendant, on having his attention called to the alert condition bythe sound and the flashing light, performs an acknowledgment operation.This operation comprises operating a key. This operation places theannunciator 200 in an alarm condition indicated by an absence of soundand a steady light at the supervisory circuit. The alarm condition isirreversible for any location at which the trouble developed. Thisirreversibility is indicated by the line 110 with the single arrowheadpointing towards the alarm condition. Thus the operator has acknowledgedthe trouble and has placed the annunciator 200 in the alarm condition.In this fashion the annunciator in this specific embodiment of theinvention maintains a record of the existence of trouble at a specificmonitored location by the steady light. At the same time the operator isundisturbed by the continuance of the unpleasant alarm sound.

If, during the alarm condition, another monitored location shoulddevelop trouble, a new'signal is transmitted to its supervisory circuit.This new signal controls the annunciator 200 to provide an alertcondition. This immediately informs the attendant of the newly developedtrouble. Upon this occurrence, the attendant will normally, againperform the acknowledgment operation with 4 the result that the alarmsound is stilled but a dual trouble light indication exists.

In some situations the attendant is aware that the described sequencehas resulted, not from a true malfunction, but from the fact thatcertain equipment at the monitored location has intentionally operatedto an unusual condition. For example, a furnace which may requireconsiderable time to cool may have been shut down. The attendant knowsthat, under these circumstances, although an alert condition isindicated, no trouble is actually involved. He therefore merelyacknowledges as described and waits. Normally, however, if the alertannunciator condition results from a true trouble condition, theattendant acknowledges as described and takes the steps to remedy thedefect. The annunciator 2% therefore remains in the alarm conditionpending the removal of the trouble or the return of the equipment intoits functioning condition.

At the time the trouble is removed, the input to the respectivesupervisory circuit returns to normal and the supervisory circuitcontrols an appropriate indicating signal. The supervisory circuit nowcontrols the annunciator 200 to indicate the flash condition. As notedheretofore, in this condition the light associated with the supervisorycircuit flashes and a buzzing sound indication is provided. As thisflash situation may result from just the temporary correction of anindicated fault, apparatus in accordance with the invention provides areversible operation between flash and alarm conditions. Thisreversibility is indicated by the double arrowheads associated with hereas indicated by the line 120. Thus if a fault is only temporarily orintermittently eliminated, the annunciator 200 reverts to the alarmcondition. If, however, the fault is fully eliminated the annunciator200 stays in the flash condition. This latter situation indicates to theattendant that the trouble condition has been cleared. It will benotedthat the flash condition is readily distinguished from the alertcondition by a difference in sound. This flash condition isdistinguished from the alarm condition with equal ease by the factthat'the lamp 475 lights intermittently or flashes. With the attendantinformed that the trouble is corrected, he simply operates theacknowledgment apparatus to return the annunicator 200 to normalcondition. This irreversible transfer from flash to normal annunciatorconditions is indicated by the single arrowhead associated with the line130. The light and sound are now both off. It will be understood, of

course, that the acknowledgment operation, while anysupervisory circuitis in the alarm condition, will have no effect on that circuit and theindicating light remains continuously on.

With this operational functioning of the annunciator 200 in mind,attention now is invited to FIG. 2 which shows the annunciator 200 inblock form. It will be seen that the annunciator comprises a number ofsupervisory circuits indicated at 400, 400A and 400B each having arespective indicating light 475, 475A and 475B. Each supervisory circuitis connected to monitor an individual location over a lead such as 401.The number of supervisory circuits corresponds to the number of remotelocations to be monitored. Each supervisory circuit may, however,monitor a number of such locations as will be seen hereafter inconnection with the description of the structures of FIG. 8. Inaddition, the annunciator comprises a common flasher circuit at 300 anda sounder circuit 500. The flasher is substantially similar to theflasher circuit shown in my aforementioned application. It is clear,however, this flasher 300 may be any of many other well known circuitarrangements for furnishing alternate pulses of suitable potential overlead 402.

The supervisory circuits each comprise circuitry responsive to troublesignals appearing on an associated monitoring lead, e.g., lead 401, foroperating the common sounder 500. Each supervisory circuit is arrangedto control the sounder 500 in accordance with the various monitoredcircuits and annunciator conditions. This control is exercised by way ofleads 404 and 405. The sounder 500 comprises novel arrangements amenablewhich to common control by all the plural supervisory circuits toestablish the required sound patterns under control of any onesupervisory circuit. It will be appreciated, of course, that undercertain circumstances the sounder described in my aforementionedapplication may also be used with the supervisory circuit 400, etc.

The acknowledgement operation is signalled over lead 403 by means of key490. This key, in this embodiment of the invention, is shown connectedin common to all the plural supervisory circuits. It is clear to thoseskilled in the art that, for particular monitoring functions, connectionto selected circuits of the plurality may be advantageous.

In FIG. 3 a block diagram illustrating the logical progression ofoperations performed in a supervisory circuit is provided. With thesupervisory circuit 400 in a normal condition, the lamp 475 isextinguished and no operating signal appears on either lead 404 or 405extending to the common sounder 500. Flasher circuit 300 lead 402 ispulsed with alternative signals of different potential values. A signalof one such potential value is used as an operating signal. Thesealternatively valued pulses are extended over lead 402 both to thesupervisory circuit 400 and to the sounder 500 as seen in FIG. 2.Clearly, with reference to FIG. 2, as this pulse signal is applied tocircuit 400, so this flasher signal is applied to the other lines of theplural supervisory circuits.

At the supervisory circuit 400 the alternative signals from the flasherare extended through the OR gate indicated at 427 to conductor 413 andthe AND gate indicated at 428. As the supervisory circuit is in thenormal condition, no corresponding signal appears on conductor 414 theAND gate 428 blocks the flasher signal from lead 406 extending to lamp475. The lamp 475 therefore remains extinguished. It will be noted inFIG. 3 that various conductors are connected by dashed lines to indicatethe connections are extended through either isolating resistors,rectifiers, transistors, or other circuit components for performingnecessary functions that will be more clearly apparent from the laterdetailed description of the supervisory circuit 400.

Assuming now that the location monitored by the supervisory circuit 400develops trouble so that a corresponding signal appears on lead 401extending to the gate circuit indicated at 420. The gate circuit 420responds to the incoming trouble signal to provide an appropriate outputover leads 407 and 408. The output over lead 407 is extended to an ANDgate 425, and, as will be seen in connection with FIGS. 4 and 5, tomemory circuit 423. Similarly the inverted signal appearing on 1 lead408 is re-inverted by the amplifier 409 as seen in connection with thefollowing discussion of FIGS. 4 and 5. This so inverted signal issimilarly applied to the memory 423.

The output signal extending over lead 408 is extended through the gatecircuit 424 to lead 409. From lead 409 it is extended to an AND gate 426which is presently closed due to the output on lead 410. The output onlead 409 is also extended to the OR circuit 429. The OR circuit 429provides an output over lead 414 to the AND gate 428. Lead 402 is in themeantime pulsed by alternate signals from the flasher 300. Duringalternate periods when conductor 402 is pulsed from the flasher 300,these signals are transmitted through OR gate 427 to the AND gate 428over lead 413. The AND gate 428 is therefore periodically energized byflasher signals over lead 413, and signals from OR gate 429 if anappropriate signal is supplied to that latter OR gate, thereforeprovides a signal for intermittently flashing the lamp 475 over lead406. With the lamp flashing and the horn or warble signal providedthrough the sounder 500, the

6 attendant is alerted by the annunciator 200 and is informed of thetrouble location.

If the trouble condition should clear, of course, the signal is removedfrom lead 401 and the circuit 420 returns to its original state. Theoperating signal is therefore removed from leads 407 and 408. The ANDgate 425 therefore blocks any output to conductor 405 to terminateoperation of the sounder 500 and quiet the horn or warble noise orsound. Similarly, of course, the OR gate 429 provides no operatingsignal to the AND gate 428 and this prevents the flasher signal fromintermittently lighting the lamp 475.

Assuming now that the trouble condition was not selfcorrecting or wasnot eliminated, before the attendant operates the acknowledgment key490. On operation of the key 490, a signal is provided over lead 403.This signal switches the memory 423. The memory 423 now removes anoperating signal from lead 411 to close the AND gate 425. Thisterminates the signal over lead 405 to the sounder 500 and operation ofthe horn is discontinued. Simultaneously, the memory 423 provides anoutput signal over lead 410 to the AND gates 426 and 435 and to the ORgate 429. As lead 409 is now providing an appropriate output and lead410 has an appropriate potential, the AND gate 426 provides a continousor steady output signal of a desired character over lead 412 to the ORcircuit 427. The OR circuit 427 now provides this steady signal to theAND gate 428 and, as the OR circuit 429 is also providing a steadysignal to lead 414 from both the output on lead 409 and from lead 410,the AND gate 428 provides a steady output over lead 406 to the lamp 475.The lamp 475 therefore remains continuously lighted. With the lamp 475continuously lighted, and the sounder 500 quiescent, the attendant knowsthat the annunciator 200 is in the alarm condition.

If now, another location should develop a trouble situation, the circuitcorresponding to 420 at the respective supervisory circuit 400A, forexample, provides an output over lead 406A, analogous to 406 discussedabove, and 405 as described. The output over lead 405 from the AND gatecorresponding to 425 at supervisory circuit 400A causes the soundercircuit 500 to again provide the horn or warble sound. Similarly, thelamp, for example, lamp 475A as supervisory circuit 400A is also flashedin a manner described. The attendant is alerted to a trouble conditionat a different location. He therefore again operates the acknowledgmentkey 490 to place the annunciator 200 in the alarm condition with thelamp 475A continuously lighted and the horn oif under control of sounder500.

If, after the annunciator is in the alarm condition, the trouble iscleared, the fault signal provided, illustratively, over lead 401 isremoved. The circuit 420 at the respective supervisory circuit 400therefore returns to its original condition. The leads 407 and 408therefore also revert to their original condition. AND gate 425 remainsclosed, while lead 409 also reverts to its original condition undercontrol of circuit 424. This closes AND gate 426 and opens AND gate 435.With AND gate 435 open, lead 404 extending to the sounder 1500 isprovided with an appropriate output so that sounder 500 provides a buzzsound which is in the nature of a steady hum. That sound indicates tothe attendant that a trouble condition is cleared. With AND gate 426closed, the steady signal to gates 427 and 428 is removed, leaving thealternate signals from lead 402 in control of these gates. As lead 410also applies its output to OR circuit 429, the AND gate 428 isintermittently opened in response to signals from flasher 300, and thelamp 475 is intermittently lighted. This informs the attendant, whichcircuit has been cleared.

If now the trouble condition should reoccur, the output on lead 409reverts to indicate the trouble by clos ing the AND gate 435 andterminating further operation of the sounder 500 while opening AND gate426 so that the lamp 475 returns to a steady lighted condition.

Assuming that the trouble condition remains clear, the attendantacknowledges the same by operating the acknowledgment key 490 again. Ondoing so, he resets the memory 423 to restore the original output toleads 410 and 411. He thereby extinguishes the lamp 475 by removing thesignal from OR gate 429 and restores the sounder 500 by closing AND gate435 to remove the operating signal from lead 404. As lead 401 isrestored to its original condition, supervisory circuit 400 is preparedfor another cycle.

The detailed circuit arrangement of the supervisory circuit 400 and thesounder 500 may be seen by reference to FIGS. 4 and respectively. Takingfirst FIG. 4 wherein the supervisory circuit 400 is shown with thevarious circuits discussed in conjunction with FIG. 3 indicated bydashed lines, it will be noted that the input to lead 401 is connectedthrough a transformer 440, whose primary is connected across asignalling circuit controlled from the remote monitored location eitherthrough appropriate switching circuits or directly. It will also benoted that a test circuit is indicated at terminal 415 Whose function issimply to permit the simulation of a fault or trouble signal todetermine that the components are functioning properly. The troublesignal may be provided by the closure of a contact set across theprimary of transformer 440; however, this condition is primarily one ofchoice and may on the contrary be provided by the interruption of anormally present signal which may be either A0 or DC. depending on theneeds of the circuit. The diodes or rectifiers D1 and D2 are connectedacross opposite ends of the secondary of transformer 440 to provide anegative potential via lead 401 to the base circuit of transistor Q1responsive to the occurrence of a trouble signal across the transformerprimary. Condenser C1 ensures that the signal is a true fault signal andnot just a transient condition resulting from various noise conditions.

Normally, transistor Q1 is off so that conductor 407 is somewhat abovethe negative potential indicated at C1 and conductor 407 is below thepositive potential indicated at +31. The negtaive potentials provided inthe system are indicated by the character C1 or C2, while the positivepotentials are indicated by the reference character +B1. Potentialslying between these two values are provided by appropriate resistancedrops connecting the same and a selected reference or neutral potenial,which may if desired be at ground, are indicated by i.

When the trouble signal occurs, condenser C1 is charged negatively asthis condenser becomes sufficiently charged, the base circuit oftransistor Q1 is biased to initiate conduction. That is, Q1 goes from anOFF to an ON condition. As a result of this conduction condition shift,the collector circuit of transistor Q1 swings toward neutral potentialin response to its turning on and conductors 407 and 408 thereforebecome considerably more positive. With the positive signal applied toconductor 408, normally on transistor Q2 turns off so that conductor 409swings negative.

Conductor 407 on swinging towards a more positive potential transmitsthat potential to the emitter circuit of normally olf transistor Q3. Asthe base circuit of transistor Q3 is biased negative by the potential onlead 411, that transistor Q3 turns on to transmit a positive signalacross the diode D3 to lead 405 extending to the sounder 500. This willturn on the horn to provide an alert signal as will be described inconjunction with the description of sounder circuit 500.

When conductor 400 swings toward negative potential, conductor 414 alsoassumes a more negative potential determined by the drop across resistorR6. Conductor 414 transmits the corresponding negative signal to thebase circuit for transistor Q4. In the meantime, lead 402 alternatesbetween negative and more positive potentials under control of theflasher 300, and when lead 413 swings, negative to follow the potentialon lead 402, both transistors Q5 and Q4 turn on in tnadem. TransistorsQ5 and Q4 will therefore come on intermittently following the potentialswings on lead 402. With transistor Q4 on, a negative voltage swing iscoupled to the base electrode of power transistor Q6. Thus, Q6 is turnedon. The light 475 is therefore intermittently lighted over lead 406 astransistor Q6 follows the intermittent conduction of Q4 and Q5 to informthe attendant which circuit had developed the alert condition.

It will be appreciated, of course, if the trouble condition isalleviated long enough to enable condenser C1 to assume a normal chargestate, i.e. a charge to the potential +131, that transistor Q1 turnsotf. Leads 407 and 408 revert to their original or normal condition andtransistors Q2 and Q3 do the same. As transistor Q2 turns on, conductor414 swings positive to shut off transistor Q4 and thus to terminateflashing of the light 475. At the same time, the turning off oftransistor Q3 terminates operation of the sounder 500. The annunciator200 therefore reverts to normal and the attendant need take no actionunless it is necessary to trace the cause of the temporary fault signal.

The attendant noting the alert condition (assuming the annunciator 200remains in that condition) now operates the acknowledgement key 490 andapplies a substantial negative potential over lead 403 and resistor R15to the base circuit of normally olf transistor O7 to turn thattransistor on. A similar potential is applied to resistor R18. With lead407 connected to the other side of resistor R18 through diode D4,however, that other side remains clamped to the neutral potential onlead 407. With transistor Q7 on, transistor Q8 turns off. As thecollector circuit of transistor Q7 swings positive, lead 411 swings inthe same direction to turn transistor Q3 off and terminate the signal onlead 405. This cuts off the horn or warble sound provided by the sounder500.

As transistor Q8 turns off, a substantial negative potential istransmitted over lead 410 to conductors 412 and 414. The latterconductor, of course, is already negative due to the negative potentialon lead 409. The negative swing on lead 410 is also transmitted to thebase circuit of transistor Q9; however, as the emitter circuit oftransistor Q9 is held negative by the potential on lead 409, thattransistor Q9 does not turn on, as yet.

With conductor 412 swinging negative, conductor 413 also swingsnegatively to establish a negative potential on the base circuit oftransistor Q5. Thus transistors Q5, Q4 and Q6 are continuouslyconducting without regard to the signals supplied over lead 402 by theflasher. The light 475 is now continuously energized. Since the horn isolf by virtue of termination of the signal on lead 405. There is thusestablished the alarm condition for the annunciator 200. Furtheroperation of the acknowledgment key 490 will have no further effect asQ8 cannot be turned on thereby.

In this alarm situation, the indicated circuit defect may be eliminated.Thus the fault indicating signal is removed from lead 401. Thetransistor Q1 turns off and transistor Q2 turns on; therefore lead 407swings in a negative direction, however transistor Q3 is already off.

When transistor Q2 turns on, lead 409 swings towards a positive valueand the same is applied the emitter circuit transistor Q9. The positivepotential on lead 409 is also transmitted through diode D6 to clamp lead412 positive. With lead 410 at a negative value, transistor Q9 initiatesconduction to apply a positive signal over lead 404. This positivesignal operates the sounder 500 to provide a steady buzz tone. This toneinforms the operator that the ammunciator condition has been changedfrom the alarm condition to a flash condition.

With lead 412 clamped at the same potential as lead 409, lead 413 canswing negative only when the flasher provides appropriate signals overlead 402. As lead 410 is still negative, the potential on lead 414 is ata corresponding value and transistors Q4 and Q5 conduct in response tothe flasher signals to flash lamp 475. On noticing the flashingcondition of the lamp 475 and the steady hum, the attendant is informedthat the trouble condition has been alleviated and knows the annunciator200 is in the flash condition.

If the trouble signal should now reappear, transistor Q1 again conductsto cut off Q2. Lead 409 is shifted to a negative value and conductor 412again swings negative. Transistors Q4, Q5 and Q6 again conductcontinuously to maintain lamp 475 continuously lighted. With lead 409negative, transistor Q9 cuts on to terminate the signal on lead 404 andshut off the sounder 500. With sounder 500 off and lamp 475 lightedcontinuously, the annunciator 200 has reverted to the alarm condition sothat the attendant is accordingly signalled.

The attendant again momentarily operates the acknowledgment key 490 ifthe annunciator stays in the flash condition to apply a substantialnegative potential through resistor R18 to the base circuit oftransistor Q8. This potential turns transistor Q3 on. This transistor Q8is turned on by operation of key 490 since no fault exists andtransistor Q1 is off. Thus lead 407 is now negative to eliminate theclamp through diode D4 on the base circuit of transistor Q3. Diode D5,of course, maintains one end of resistor R15 at the positive potentialof lead 409 to prevent the negative potential on lead 403 from beingapplied to the base circuit of Q7. Transistors Q7 and Q8 are now intheir normal or original condition.

Transistor Q8 on turning on, removes the negative potential from lead410 and the potential on that lead swings positive. Hence conductor 414is now maintained at a potential which holds transistors Q4, Q5 and Q6cut oif. The annunciator 200 is now in the normal condition and isprepared for another cycle.

Referring now to FIG. 5 showing the details of the sounder 500, it willbe seen that it is connected in common to each supervisory circuit 400,400A and 400B by means of two separate input leads 404 and 405 and isprovided with pulses of alternate potential over lead 402 from theflasher 300. Lead 405 is connected to the base circuit of normally ontransistor Q20 and lead 404 is connected to the base circuit of normallyon transistor Q21. Transistors Q20 and Q21 each control a multivibratorcircuit arrangement comprising the transistors Q24 and Q25 which feedthe transformer 550. Transformer 550, in turn, feeds the amplifiers Q26and Q27, which power a loud speaker (not shown) over transformer 560.The multi-vibrator is normally unoperated unless controlled bytransistors Q20 or Q21 in response to a signal transmitted over eitherleads 404 or 405 respectively and when operated provides a frequencycorresponding to the transistor initiating its operation.

Several unusual features are incorporated in this circuit whereby theflasher signals over lead 402 are applied to intermittently turn themulti-vibrator on under control of transistor Q20 so that the sound ofconstantly varying or intermittent intensity is derived, while a simplefeed-back circuit connected between Q20 and Q21 permits signals on lead405 to override signals on lead 404, thereby ensuring that the alertsound is provided in prefer ence to any other.

It will be recalled that when a trouble situation occurred that set theannunciator 200 in the alert condition by the flashing lamp 475 that ahorn signal resulted from the signal over lead 405. The signal over lead405 comprises a positive swing as transistor Q3 turns on and this causesthe base circuit of transistor Q20 to swing positive. Transistor Q20therefore turns off. It will be noted at this time that if transistorQ21 were oif the negative swing in the collector circuit of transistorQ20 is applied to the base circuit of transistor Q21 through resistorR40, and transistor Q21 is turned on. In any event, this negative biasis held on the base circuit of transistor Q21 so that a signal on lead404 cannot turn Q21 oil. This arrangement gives the alert signal, thehorn signal controlled by lead 405, precedence and prevents interferencetherewith by a signal indicating a flash condition of the annunicator200.

Presuming now that transistor Q20 is turned oil? by a positive signal onlead 405, its collector circuit swings negative. A correspondingpotential swing is transmitted through resistors R40 and R45respectively causing the base circuit of transistors Q21 and Q22 tofollow that swing. Both transistors Q21 and Q22, therefore, turn on, or,if on, remain on. Transistor Q22 turns on through a circuit includingalternately conducting multi-tvibrator transistors Q24 and Q25. Thetransistors Q24 and Q25 turn on and olf at a rate determined by the RCcircuits connected thereto. Included in these circuits is the lowresistance R50.

In the on condition, the transistor Q21 collector circuit is positive.Thus this circuit acts to bias the base circuit of transistor Q23 off.Hence, as transistor Q21 conducts, transistor Q23 is ofl except whennegative signals appear on lead 402 from the flasher 300. At that timetransistor Q23 conducts through resistors R50 and R55 and transistorQ22. As transistor Q23 conducts through the voltage divider comprisingresistor R50, the frequency of the multivibrator is changed. Astransistor Q23 is conducting only intermittently under the influence offlasher 300, the signal output to transformer 550, to transistors Q26and Q27 and to transformer 560 to the speaker is at a constantly varyingfrequency. This varying frequency causes the speaker to emit an audiblehorn or warble signal of demanding and alerting character.

The attendants subsequent operation of the acknowledgment key 490 turnsoff transistor Q3 at the supervisory circuit to remove the signal fromlead 405. Transistor Q20 therefore turns on; however, the bias on thebase circuit of transistor Q21 does not change sufliciently to turn thislatter transistor off. The positive swing transmitted through resistorR45, however, does turn oif transistor Q22 to prevent further conductionthrough any of the transistors Q23, Q24 and Q25. Accordingly, the soundis terminated and the annunciator 200 is in the alarm condition. If nowanother supervisory circuit such as 400A should transmit an alert signalover lead 405, the procedure for providing the warble sound is repeated.

Assuming now that a flash conditon has occurred and that transistor Q9at the supervisory circuit is conducting to transmit a positive signalover lead 404. The end of resistor R34 connected to the base circuit oftransistor Q21 swings positive to turn transistor Q21 off. The collectorcircuit of Q21 therefore swings negative to bias the base circuits ofboth transistors Q22 and Q23 negative and each turns on. Transistor Q23now remains on continuously without regard to the positive swings onlead 402, as the base circuit of transistor Q23 is biased negative bythe collector circuit potential of Q21. With transistors Q22 and Q23conducting continuously, transistors Q24 and Q25 alternately conduct.This alternate conduction provides an alternating output throughtransformers 550 and 560 for operating the loud speaker to provide asteady buzz sound indicating the flash condition.

If during the flash condition a signal should appear on lead 405indicating an alert condition, transistor Q20 turns off to turn Q21 on,as explained. The flasher signal on lead 402 now controls Q23 so that itconducts alternately to provide the alert signal from the loud speakeras explained. Likewise if the flash condition should revert to an alarmcondition transistor Q9 turns 0E. This removes the signal from lead 404and transistor Q21 turns on. This 11 cuts olf transistors Q22, Q23, Q24and Q25 and the sound is terminated while the annunicator reverts to thealarm condition.

With the sounder 500 controlled to indicate the fiash condition,acknowledgment key 490 is operated to turn transistor Q9 off at thesupervisory circuit. This cuts on the signal on lead 404. Transistor Q21then turns on. When Q21 turns on, of course Q22 is biased oil andfurther loud speaker operation is terminated. The annunciator is now atnormal and the cycle may now be repeated.

In the annunciator arrangement shown in FIG. 6 a simplified supervisorycircuit 600 is provided for accomplishing certain purposes of thepresent invention. This circuit is illustrative of an arrangementadapted to operate a variant sounder indicated by the box 650. Thissounder is similar in character to that shown in the aforementionedapplication instead of to the sounder just described. The operation ofthat described sounder, however, may easily be accommodated with theinstant supervisory circuit. The sounder 650 is also under control ofplural supervisory circuits 600A and 60013, each of which,

is provided with an incoming lead 601A and 601B respectively forreceiving trouble signals and these circuits are similar to supervisorycircuit 600. In addition, the acknowledgment key 690 is provided. Thiskey transmits a timed acknowledgment signal to the supervisory circuitsand to sounder 650 in a manner similar to that explained in theaforementioned application. If desired, of course, a separate key may beprovided for each supervisory circuit.

Condenser C8 may be either connected to the base circuit of transistorQ50 as indicated by the dashed connection or to the collector circuit oftransistor Q50 and the base circuit of transistor Q51 as indicated bythe starred connection. This condenser C8 is adapted to charge onsignals of considerably shorter duration than that contemplated forcondenser C1 in FIG. 4. If condenser C8 is connected to the base oftransistor Q50, the collector circuit of transistor Q50 is connected toC1 potential as indicated by the dashed line therebetween.

In the one charging path, a resistor R100 is shown connected between thebase and collector circuits of transistors Q50 and Q51 respectively toprovide an extremely simple arrangement for holding Q50 and Q51 in adesired condition as will be explained.

It will be noted that the sounder 650 is operated through a condenserC25 and diode D25 instead of through the transistors Q3 and Q9 as shownin FIG. 4. Thus instead of providing both the horn or warble sound andthe steady tone as described in the aforementioned application, only asteady tone is provided. Also, as no flasher circuit input is providedto the supervisory circuits 600, 600A or 6003, the indicating lightsshown at 625, 625A and 625B are continuously lighted when signalling.

Assuming first the connection of condenser C8 to the base circuit of Q50and the use of resistor R100, it will be seen that a negative faultsignal appearing on lead 601, switches transistor Q50 on. Transistor Q50may also be switched on for a simulated trouble signal applied at testterminal 609 for testing the operative sequence of the supervisorycircuit.

The positive swing occurring in the collector circuit of transistor Q50is transmitted to the base circuit of transister Q51 to turn Q51 01f. Asthe collector circuit of Q51 swings negative, this potential istransmitted through resistors R100 and R110 respectively. The negativepotential transmitted through resistor R100 will maintain Q50 onregardless of the removal of the trouble signal on lead ,601 as resistorR100 is considerably smaller than resistor R105. The signal transmittedthrough R110 of course turns transistor Q52 on so that its emittercircuit swingsnegative, and its collector circuit positive.

As the emitter circuit of Q52 swings negative, amplifier transistor Q53switches on to light lamp 625 so that the attendant knows the locationof the trouble. Capacitor C25 now also charges in a directioncorresponding to the positive potential swing in the collector circuitof Q52 to thereby transmit a pulse through diode D25 for operating thesounder circuit 650. Thus the associated loud speaker emits a tone asdescribed in the aforementioned application.

It will be noted that if the trouble signal is now removed from lead601, transistor Q50 is maintained conductive due to the negativepotential transmitted through resistor R100. If resistor R is not used,of course Q50 would turn off in response to removal of the fault signal,thereby causing Q51 to conduct and terminate operation of Q52 and lamp625. The sounder 650 remains on, however, in either case as the signalto the sounder 650 trips a memory therein which retains the sounderoperated until the acknowledgment key 690 is operated, as explained inthe aforementioned application. As in one case, however, the light turnsoff, the attendant knows that the trouble is alleviated.

The acknowledgment key 690 on operation provides a negative signal tothe base circuit of transistor Q51 to turn this transistor on. As thecollector circuit of Q51 swings positive, Q50 and Q52 turn off. As theacknowledgment signal is applied for a predetermined time in any wellknown manner of application Q51 will remain on only for that period, ifthe trouble signal is not removed. If the trouble signal is not removed,transistor Q50 turns back on as soon as the acknowledgment signal isremoved and the lamps 625 relight as explained. If transistor Q52 isonly turned off momentarily, capacitor C25 does not rechargesufficiently to enable the subsequent conduction through Q52 to resultin the transmission of a pulse through D25 to operate the sounder 650.The sounder 650 is turned off on operation of the acknowledgment key 690through the ganged switch provided therefor, however any other switcharrangements are possible. No sound is therefore provided after theacknowledgment operation.

With the lamps 625 remaining lighted, the attendant knows the alarmcondition is maintained. He therefore periodically operates the key 690to determine if the trouble signal is removed in the event resistor R100is provided. If the trouble signal has been removed, transistor Q50remains otf following the acknowledgment signal and Q51 remains on. Ifresistor R100 is not provided, of course, as soon as the trouble signalis relieved Q50 turns off and Q51 turns on. In either event Q51 turningon causes Q52 to remain off and extinguish lamps 625. Thereafter thesupervisory circuit 600 is prepared for another cycle.

When the starred connection from lead 601 to the base circuit oftransistor Q51 is provided, transistor Q51 is normally maintained on bya negative signal and is turned off responsive to the removal of thenegative signal indieating a fault. On turning off transistor Q51, thecollector circuit of this transistor swings negative so that thebase-emitter circuit of transistor Q50 conducts. The lamp 625 and thesounder 650 are operated as before described, and the attendant operatesthe acknowledgment key 690 to terminate operation of the sounder 650.

In the arrangement shown in FIG. 7, a simpler version of the supervisorycircuit shown in FIG. 6 is illustrated. This circuit is also intended tooperate with a sounder such as 650 described in the aforementionedapplication.

In this case the input is connected from lead 701 directly to normallyotf transistor Q60. This transistor switches on, as soon as capacitorC40 is charged sufiiciently by a negative fault or trouble signal.Likewise transistor Q60 may be switched on by a simulated fault signalapplied at test terminal 709. Amplifier transistor Q61 therefore alsoswitches on to light the lamp 710, while the pulse provided bytransistor Q60 is transmitted over capacitor C45 and over diode D60 thusto operate the sounder 650 to provide the alerting tone. The attendantsubsequently acknowledges by turning ofi the sounder as described in theaforementioned application, but lamp 710 remains lighted as long astransistor Q60 is Assuming that the trouble signal is thereafterterminated for a sufiicient period to permit capacitor C40 to discharge,transistor Q60 turns off. This in turn switches Q61 off and extinguishesthe lamp 710 so that the attendant knows the trouble is alleviated.

In FIG. 8 another form of a supervisory circuit for use in accomplishingcertain of the purposes of the present invention is illustrated. Withthis arrangement, three dilferent lamp circuits are provided for eachsupervisory circuit. Each lamp circuit is utilized to signal a fault ata different location. Also the circuit shown in FIG. 8 incorporatescertain features of the type of supervisory circuit shown in theaforementioned application in that it utilizes a memory comprisingtransistor Q85 and Q86 and alternate signals over lead 802 from aflasher circuit but arranged to operate with a sounder such as sounder500 illustrated in FIG. 5.

Thus normally separate inputs from respective locations are provided atleads 801, 801A and 8013 while terminal 809 is used to apply a simulatedfault signal for test purposes. Transistors Q80, Q90 and Q95 connectedto the respective input leads are normally 01? as are respectivelyassociated lamps, red lamp 810, green lamp 810A and amber lamp 810B. Thelamp colors are, of course, a matter of choice. Each lamp is associatedwith an individual supervisory circuit. The lamps, further, each emit adifferent color so that each monitored location associated with thesupervisory circuit may be identified.

Responsive to a trouble signal at one of the monitored locations, forexample, a trouble signal at that location associated with lead 801,transistor Q80 initiates cond-uction. This conduction biases the baseand emitter circuits of transistors Q81 and Q88 respectively in apositive direction. Transistor 81 therefore turns ofi and, as itscollector circuit swings negative, a corresponding pulse is applied overlead 822 to the respective base circuit of transistors Q83 and Q85.Transistor Q85 begins to conduct and its collector circuit swingspositive to render transistor Q86 nonconductive. With transistor Q86off, its collector circuit swings negative to transmit a correspondingpulse to the base circuit of transistor Q88 to turn Q88 on.

Transistors Q83 and Q84 now also conduct in tandem responsive tointermittent or alternate signals over lead 802 from the flasher. Thebase circuit of amplifier transistor Q89 therefore swings negative whenQ83 and Q84 come on and it intermittently lights the red lamp 810.

Fault signals appearing at either leads 801A or 801B apply a negativesignal at the base circuit of respective transistors Q90 and Q95. Eachtherefore also conducts to turn respective amplifier transistors Q91 andQ96 on respectively. When this occurs the respective green and amberlamps 810A and 810B light to signal the fault condition to theattendant.

When the base circuit of transistor Q88 swings negative, this transistorturns on to transmit a positive pulse to the sounder over lead 805. Thislead corresponds to lead 405 described in connection with sounder 500.The pulse over lead 805 has substantially the same effect as describedfor sounder 500 in causing the sounder to provide a warble toneindicating the alert condition of the annunciator.

The attendant responds to this condition by operating the acknowledgmentkey 890 to transmit a negative pulse over lead 803. This pulse turnstransistor Q86 on. The conduction of this transistor, in turn,terminates conduction by transistor Q85. As the collector circuit of nowconducting transistor Q86 swings positive, this swing cuts offtransistor Q88 to terminate the war-ble sound. The negative swing in thecollector circuit of transistor Q85 14 is now transmitted to the basecircuit of Q84 so that transistors Q83 and Q84 now conduct continuouslyto maintain lamp 810 continuously lighted.

If now, the trouble signal should be corrected, conduction throughtransistor Q is terminated and transistor Q81 turns on. As the collectorcircuit of Q81 swings positive, a corresponding pulse is transmitted tothe base circuit of transistor Q86 over lead 822 to turn Q86 off and Qon. As Q85 comes on, the emitter circuit of Q87 is biased positive,while the base circuit of Q87 is biased negative from the collectorcircuit of cut off transistor Q80. Transistor Q87 therefore switches onto transmit a positive pulse over lead 804 to the sounder. This positivepulse has the same elfect as a positive pulse described over lead 404 incausing the sounder to emit a steady tone or hum. In the meantime thenegative swing in the collector circuit of Q86 is transmitted to thebase circuit of Q83. At the same time, alternate flasher signals areapplied to the base circuit of Q84. Transistors Q83 and Q84 thereforeconduct in tandem. Thus current flows intermittently to light lamp 810.

The attendant is now informed of the fiash condition and operates theacknowledgment key again to apply a signal over 803 for turning Q86 on.When this occurs Q85 goes off to bias the emitter circuit of Q87negative and to turn this latter transistor off. This terminates thesignal over lead 804 and the sounder now reverts to the quiescent state.The positive swing in the collector circuit of transistor Q86 istransmitted to the base circuit of Q83. Since the collector circuit ofQ81 is positive, this terminates further conduction through transistorsQ83 and Q84 to maintain lamp 810 off. The supervisory circuit is nowready for another cycle.

From the preceding description of the invention it will be appreciatedthat the same represents a considerable improvement in facilitating theutilization of electronic annunciators, however, it is believed that theinvention is not limited to the particular embodiment or arrangementshown herein, but that its concepts are more fully set forth in theappended claims.

I claim:

1. A sound control circuit for use in an annunciator wherein a pluralityof normally inoperative circuits is provided for receiving respectivefault signals, the improvement comprising a normally conductive firsttransistor connected in common with each of said plurality of normallyinoperative circuits, a current generator arranged to generate a currentof any one of a number of frequencies, a second normally conductivetransistor connected in common with each of said plurality of circuits,means operated for rendering said first transistor nonconductiveresponsive to the receipt of a fault signal by any one of said pluralityof circuits, means thereafter controlled for operating said generator togenerate current at a predetermined first frequency for operating asignal at a corresponding frequency, means for rendering said secondtransistor nonconductive responsive to the disappearance of a faultsignal to operate said generator to generate current at second frequencyto operate a signal at said second frequency, and means controlled bysaid first nonconductive transistor for maintaining said secondtransistor conductive irrespective of the disappearance of a faultsignal at another one of said plurality of circuits.

2. The arrangement claimed in claim 1 in which said maintaining meanscomprises an OR gate connected between said first nonconductive and saidsecond conductive transistors.

References Cited by the Examiner UNITED STATES PATENTS 2,600,132 6/1952Seaton 340--213 2,659,07-1 1-1/1953 Dohm 340-329 2,695,400 11/1954Snitjer 3402l3 2,709,249 5/1955 Sperry 340-213 (Other references onfollowing page) 1 5 UNITED STATES PATENTS Marmorstone 340--213 Ross340213 Warren 340--213 Rodgers 340213 5 Ebel 340-213 Beguin 340-213Keller 340-213 Vitt et a1 340-2132 Noreen et a1 340213.2 1O

16 OTHER REFERENCES Universal Panalarm 50, publication by PanalarmProducts, In-c., Chicago, 111., copyright 1952, received July26,-1956(pages 13, 24, and 25).

Brown et a1. Transistors: A New Class of Relays, in Control Engineering,Dec. 1956, pp. 70-76.

NEIL C. READ, Primary Examiner. BENNETT G. MILLER, Examiner.

1. A SOUND CONTROL CIRCUIT FOR USE IN AN ANNUNICATOR WHEREIN A PLURALITYOF NORMALLY INOPERATIVE CIRCUITS IS PROVIDED FOR RECEIVING RESPECTIVEFAULT SIGNALS, THE IMPROVEMENT COMPRISING A NORMALLY CONDUCTIVE FIRSTTRANSISTOR CONNECTED IN COMMON WITH EACH OF SAID PLURALITY OF NORMALLYINOPERATIVE CIRCUITS, A CURRENT GENERATOR ARRANGED TO GENERATE A CURRENTOF ANY ONE OF A NUMBER OF FREQUENCIES, A SECOND NORMALLY CONDUCTIVETRANSISTOR CONNECTED IN COMMON WITH EACH OF SAID PLURALITY OF CIRCUITS,MEANS OPERATED FOR RENDERING SAID FIRST TRANSISTOR NONCONDUCTIVERESPONSIVE TO THE RECEIPT OF A FAULT SIGNAL BY ANY ONE OF SAID PLURALITYOF CIRCUITS, MEANS THEREAFTER CONTROLLED FOR OPERATING SAID GENERATOR TOGENERATE CURRENT AT A PREDETERMINED FIRST FREQUENCY FOR OPERATING ASIGNAL AT A CORRESPONDING FREQUENCY, MEANS FOR RENDERING SAID SECONDTRANSISTOR NONCONDUCTIVE RESPONSIVE TO THE DISAPPEARANCE OF A FAULTSIGNAL TO OPERATE SAID GENERATOR TO GENERATE CURRENT AT SECOND FREQUENCYTO OPERATE A SIGNAL AT SAID SECOND FREQUENCY, AND MEANS CONTROLLED BYSAID FIRST NONCONDUCTIVE TRANSISTOR FOR MAINTAINING SAID SECONDTRANSISTOR CONDUCTIVE IRRESPECTIVE OF THE DISAPPEARANCE OF A FAULTSIGNAL AT ANOTHER ONE OF SAID PLURALITY OF CIRCUITS.